diff --git a/extra/project-euler/034/034.factor b/extra/project-euler/034/034.factor new file mode 100644 index 0000000000..83cffeb248 --- /dev/null +++ b/extra/project-euler/034/034.factor @@ -0,0 +1,47 @@ +! Copyright (c) 2008 Aaron Schaefer. +! See http://factorcode.org/license.txt for BSD license. +USING: combinators.lib kernel math.ranges project-euler.common sequences ; +IN: project-euler.034 + +! http://projecteuler.net/index.php?section=problems&id=34 + +! DESCRIPTION +! ----------- + +! 145 is a curious number, as 1! + 4! + 5! = 1 + 24 + 120 = 145. + +! Find the sum of all numbers which are equal to the sum of the factorial of +! their digits. + +! Note: as 1! = 1 and 2! = 2 are not sums they are not included. + + +! SOLUTION +! -------- + +! We can reduce the upper bound a little by calculating 7 * 9! = 2540160, and +! then reducing one of the 9! to 2! (since the 7th digit cannot exceed 2), so we +! get 2! + 6 * 9! = 2177282 as an upper bound. + +! We can then take that one more step, and notice that the largest factorial +! sum a 7 digit number starting with 21 or 20 is 2! + 1! + 5 * 9! or 1814403. +! So there can't be any 7 digit solutions starting with 21 or 20, and therefore +! our numbers must be less that 2000000. + +digits [ digit-factorial ] sigma = ; + +PRIVATE> + +: euler034 ( -- answer ) + 3 2000000 [a,b] [ factorion? ] subset sum ; + +! [ euler034 ] 10 ave-time +! 15089 ms run / 725 ms GC ave time - 10 trials + +MAIN: euler034 diff --git a/extra/project-euler/common/common.factor b/extra/project-euler/common/common.factor index c875a440ba..2e718ab5a2 100644 --- a/extra/project-euler/common/common.factor +++ b/extra/project-euler/common/common.factor @@ -7,11 +7,11 @@ IN: project-euler.common ! Problems using each public word ! ------------------------------- -! cartesian-product - #4, #27 +! cartesian-product - #4, #27, #29, #32, #33 ! collect-consecutive - #8, #11 ! log10 - #25, #134 ! max-path - #18, #67 -! number>digits - #16, #20, #30 +! number>digits - #16, #20, #30, #34 ! propagate-all - #18, #67 ! sum-proper-divisors - #21 ! tau* - #12 diff --git a/extra/project-euler/project-euler.factor b/extra/project-euler/project-euler.factor index 329a1b9668..74577debd9 100644 --- a/extra/project-euler/project-euler.factor +++ b/extra/project-euler/project-euler.factor @@ -1,4 +1,4 @@ -! Copyright (c) 2007 Aaron Schaefer. +! Copyright (c) 2007, 2008 Aaron Schaefer. ! See http://factorcode.org/license.txt for BSD license. USING: definitions io io.files kernel math.parser sequences vocabs vocabs.loader project-euler.ave-time project-euler.common math @@ -9,7 +9,8 @@ USING: definitions io io.files kernel math.parser sequences vocabs project-euler.017 project-euler.018 project-euler.019 project-euler.020 project-euler.021 project-euler.022 project-euler.023 project-euler.024 project-euler.025 project-euler.026 project-euler.027 project-euler.028 - project-euler.029 project-euler.030 project-euler.067 project-euler.134 + project-euler.029 project-euler.030 project-euler.031 project-euler.032 + project-euler.033 project-euler.034 project-euler.067 project-euler.134 project-euler.169 project-euler.173 project-euler.175 ; IN: project-euler